Aspherical multifocal intraocular lens

ABSTRACT

A multifocal intraocular lens has an anterior lens surface which includes a first optic of a first radius and a second optic of a different radius. The posterior surface of the lens include an aspheric surface.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention is for an intraocular lens that is typically usedas a replacement for the natural lens of the human eye. In the eventthat the natural lens of the human eye is removed, for example duringcataract surgery, an intraocular lens is typically implanted in the lenscapsule as a replacement for the natural lens.

2. Description of Related Art

There are several types of intraocular lenses (IOL) that have beendeveloped. They include aspheric lenses, multifocal lenses andaccommodating lenses. Also improved haptics for securing the lens withinthe lens capsule have been developed. These designs to some extentresult in aberrations and create a halo effect or result in reducedcontrast and/or brightness.

BRIEF SUMMARY OF THE INVENTION

The current invention overcomes the drawbacks in the prior art with aunique configuration. The lens of the current invention is formed as anaspheric lens with an added lens surface formed on the posterior portionof the lens. Integral with the lens is a haptic system that securelymounts the lens centrally within the lens capsule and thus minimize any“halo” effect or other aberrations.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic view of the human eye.

FIG. 2 is a side view of a conventional intraocular lens.

FIG. 3 is a side view of an intraocular lens according to an embodimentof the invention.

FIG. 4 is a front view of the lens shown in FIG. 2

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 it can be seen that the relevant portions of the eyefor purposes of this invention are as follows. Eye 100 has a naturallens capsule 110 in which the natural lens is located and pupil 113,which is surrounded by iris 116. The area forward of the lens capsule110 is generally referred to as the anterior chamber 112 and the arearearward of the lens capsule 110 is referred to as the posterior chamber132. The lens capsule 110 is held in place by ciliary zonules 133 whichextend between the lens capsule 110 and the ciliary body 118. The space131 between the iris 116 and the ciliary zonules 133 is referred to asthe ciliary sulcus 131. The eye also includes cornea 114, sclera 122,choroaid 124, retina 126, fovea 128 and optic nerve 130.

For cataract surgery, a small incision is normally made at the junctionof cornea 114 and sclera 122 and the natural lens can be removed fromthe lens capsule 110 by phacoemulsification, for example. An intraocularlens (IOL) is then implanted within the lens capsule through the sameinitial incision.

FIG. 2 discloses a conventional aspherical lens 10 which includes acentral lens portion 15 having opposing convex lens surfaces 14 and 13.Suitable haptics 11 and 12 extend outwardly from the lens portion 15 forsecuring the lens within the lens capsule.

FIG. 3 illustrates an embodiment of the invention. Intraocular lens 20has a posterior surface 24 which is aspherical in shape. Posteriorradius of surfaces 29 are of equal value. The anterior surface 51 oflens 20 has a first aspherical lens surface 23 which has a radius equalto radius of surfaces 29 and a second lens surface 27 of a smallerradius, thus forming a higher power lens 26 than that of lens surface23.

The radius of surface 27 is less than that of lens surface 23 so that informing lens 26, a flat surface 28 will be formed on the outer peripheryof the anterior side of the lens as shown in FIGS. 3 and 4. Flat surface28 lies in a plane that is parallel to the longitudinal axis 62 of thelens.

FIG. 4 illustrates the haptics utilized to secure the lens within thelens capsule. The haptics are formed in the manner disclosed in U.S.Pat. No. 6,261,321, the entire contents of which is hereby incorporatedby reference thereto. Upper haptic 21 includes vertical legs 33, 34 andcross member 35 extending between legs 33 and 34. Upper haptic 51 alsoincludes a pair of footplates 31 and 32. Legs 33, 34 and cross member 25circumvent an opening 46. The footplates are preferablylentricular-shaped.

Lower haptic 22 is formed similar to haptic 51 and includes lower legs43, 44 and cross member 45 extending between legs 43 and 44. The legs,cross member 45 and lower lens 26 circumvent opening 47. Lower haptic 52also includes a pair of footplates 41 and 42 of lenticular shape.

Lenses 20 may be formed from a single body of a conventional materialutilized for intraocular lens such as acrylic with twenty-six percentwater. Lens surface 26 can be formed by using a Fast Tool Systemavailable from Ametek Precitech, Inc., located in Keene, New Hamshire.The conic bi-aspheric shape of the lens can be determined according tothe methodology described in U.S. Pat. No. 7,350,918, the content ofwhich is hereby expressly incorporated herein by reference thereto.

The distance optic on the multifocal surface is approximately 50 to 70percent of the optical surface, and the near segment is about 50-30percent of the optic, with the preferred distribution of optic beingabout 60 percent distance are 40 percent for near.

Although the present invention has been described with respect tospecific details, it is not intended that such details should beregarded as limitations on the scope of the invention, except to theextent that they are included in the accompanying claims.

I claim:
 1. A bifocal lens comprising: a posterior aspheric lens surfacehaving a first radius of curvature, an anterior aspheric lens surface,said anterior aspheric lens surface having a first aspheric distanceoptic portion having a radius of curvature equal to the first radius ofcurvature of the posterior aspheric lens surface, a second near opticportion having a radius of curvature less than that of the first portionthereby forming a second optic surface on the anterior lens surface, thefirst aspheric distance optic portion having a perimeter and the secondnear optic portion having a perimeter, a flat surface extendingoutwardly from the entire radially outer periphery of the anterior lensnear optic portion, and a first haptic extending from a top portion ofsaid bifocal lens and a second haptic extending from a lower portion ofsaid bifocal lens, each haptic including a first and second legextending from the bifocal lens and a cross member extending between thelegs, and a footplate located at a distal end of each leg.
 2. A bifocallens as claimed in claim 1 wherein the flat surface lies in a planewhich is parallel to a longitudinal axis of the lens.
 3. A bifocal lensas claimed in claim 1 wherein the distance optic portion on the anteriorsurface is about 50% to 70% of the anterior surface of the lens and thenear optic portion is about 50% to 30% of the anterior surface of thelens.
 4. The bifocal lens of claim 1 wherein the distance optic portionon the anterior surface is about 60% of the anterior surface and thenear optic on the anterior surface is about 40% of the anterior surface.5. A bifocal lens according to claim 1 wherein the posterior asphericallens surface, the anterior aspherical distance optic portion and thesecond near optic portion of the anterior aspheric surface are convex.6. A bifocal lens comprising a lens body having an outermost annularcircumferential edge and having a posterior aspheric lens surface havinga first radius of curvature and an anterior aspheric lens surface havinga first aspheric distance optic having a radius of curvature equal tothe first radius of curvature of the posterior aspheric lens surface anda second near portion having a radius of curvature less than that of thefirst portion thereby forming a flat surface extending outwardly from anouter periphery of the second near portion to the annularcircumferential edge of the lens body; and a first haptic extending froma top portion of said lens body and a second haptic extending from alower portion of said lens body, each haptic including a first leg and asecond leg extending from the lens body and a cross member extendingbetween the legs, and a footplate located at a distal end of each leg.